I am trying to pass a value from a VF form into my controller, however the parameter is always staying as Null.
VF Code:
<apex:repeat value="{!ProdCVSiteInfo}" var="p">     
        <apex:commandButton value="Add" action="{!addProd}" style="vertical-align: top; padding:3px;">
            <apex:param name="selectedProducts" value="{!p.Id}" assignTo="{!selectedProducts}"/>  
        </apex:commandButton>
</apex:repeat>

Controller
public String selectedProducts {
get;
set {selectedProducts = value;}
}

Where am I going wrong as i have done this previously and the code looks the same, can't seem to see the error.